Increase in scale and complexity of a disk array system has advanced with recent increase in quantity of data used in an information processing system. The number of disk drives mounted in the disk array system has increased with the advance of increase in scale and complexity of the disk array system. Control boards having a plurality of electronic circuits different in operating voltage for controlling reading/writing of data from/in the disk drives are mounted in the disk array system, so that various kinds of power units must be used.
On the other hand, greater reduction in size of the disk array system has been required for effective use of a limited installation space. Control boards must be mounted densely in such a limited space because of the reduction in size. Therefore, a mechanism for performing maintenance of the disk array system efficiently, such as simplification of wiring for supplying electric power to the control boards, need to be provided in the disk array system.